Method and apparatus for grinding



9 1950 w. G. EALDENHOFER 2,534,941

METHOD AND APPARATUS FOR GRINDING Filed Jan. 16, 1948 INVENTGR WILLIAM aBfiLflENI-IQFER a 9% ATTQRNEVE Patented Dec. 19, 1950 METHOD ANDAPPARATUS FOR GRINDING William G. Baldenhofer, Springfield, Ohio, as-

signor to The Thompson Grinder Company, Springfield, Ohio, a corporationof Ohio Application January 16, 1948, Serial No. 2,566

4 Claims.

This invention relates to methods and apparatus for grinding workpieces,and particularly to such methods and apparatus in connection with theforming of workpieces having complex convolutions or relative deep slotstherein.

Workpieces having complex configurations or deep slots are oftenencountered in industry and comprise such elements as die segments andthe like. Such work members may be formed to a high degree of accuracyand it is customary for the final operation on such articles to becarried out on a grinding machine.

The usual manner of forming such members is to mount them in a suitablefixture on the table of a grinding machine and to traverse them beneatha properly formed grinding wheel. The wheel in such case is formed byany suitable dressing device and preferably is shaped by a crushdressing roller according to modern and well known practices.

The disadvantage with a grinding operation of this type is that a longtraverse past the wheel must be made even for very short workpieces inorder togrind the slot or configuration of the workpiece from side toside. As an example, considering a workpiece, say, an inch across andwhich is to have a one-half inch deep slot ground therein by a 12 inchwheel, a total table traverse relative to the wheel of about 7 inches isrequired. This not only appreciably lengthens the grinding cycle, butthe physical arrangement of the wheel and workpiece is such that it isdifficult properly to supply cooling fluid to the wheel.

The primary object of the present invention is to provide a method andapparatus for grinding workpieces of the type referred to above and inwhich the foregoing difiiculties are eliminated.

Another object is to provide a method and apparatus for grinding slottedworkpieces and the like such that the speed of the grinding cycle isgreatly increased.

A still further object of this invention is the provision of a methodand apparatus for grinding slotted workpieces and. the like wherein theamount of relative movement between the wheel and workpiece is reducedto a minimum thereby requiring the shortest possible time to accomplishthe grinding operation.

It is also an object of this invention to provide 7 become more apparentupon reference to the following description taken in connection with theaccompanying drawings in which:

Figure 1 is a side view of a typical grinding wheel arrangementaccording to this invention and adapted for practicing the methods ofthis invention;

Figure 2 is an enlarged fragmentary view showing the wheel in grindingengagement with one of the workpieces on which it operates;

Figure 3 is a plan section taken on the line 33 of Figure 2; and

Figure 4 is a diagrammatic view showing one form of electrical controlcircuit for controlling the machine of this invention.

Referring to the drawings, the machine shown therein comprises a bed 10on which is slidably mounted a table [2. The table may be powered inreciprocatory movement on the bed by any suitable means such as by thehydraulic motor indicated at M.

Mounted adjacent to or connected with the bed I!) is a column I6 andmounted on the column for vertical reciprocating movements is a saddle[8 which carries a wheel head structure 20 which may be movable in thesaddle in a horizontal direction.

The saddle it? is slidable on the guideways 22 on the column and ismovable in the vertical direction by a nut and screw arrangementindicated at 24. The screw is preferably journaled in the column in anysuitable manner and is arranged for being driven through the bevel gears2-5 by a horizontal shaft 28 and hand wheel 36 connected therewith.

Mounted in the wheel head 20 is a grinding wheel 32 which is secured tothe end of a shaft 34 rotatable in a horizontal plane. The shaft 34 hasconnected therewith a main drive motor Ml which is operable whenenergized to drive the wheel at grinding speeds and also associated withthe said shaft is an auxiliary motor M2 energizable for driving thewheel at dressing speeds. As an example of these speeds, a typicalgrinding speed has a surface speed of approximately 6,000 feet a minutefor the wheel while the crushing speed is a matter of from 200 to 400feet per minute. It is understood that these motors could be arrangedfor driving the shaft 34 in any suitable manner and there could beclutch means and. the like for selectively connecting them with theshaft if so desired.

The wheel 32 is enclosed in any suitable shield as, for example, thedrum-like shield 36 indicated in the drawings. This shield is aperturedon both sides on a level with the shaft 34 as at 38 in Figure 2 and thusprovides access to the wheel for the workpieces 4f] which are mounted oneither side of the wheel in spaced relationship therewith and coplanarin a horizontal plane with the axis of the shaft 34. These workpiecesmay be supported in any suitable sort of fixture, and for the purpose ofillustration there are shown the relatively simple standards A l which,as is best seen in Figures 2 and 3, comprise the machined fiat areas 56for locating the workpiece and a clamping screw 58 which can betightened down on the workpiece when properly positioned and rigidlyretain it in the fixture.

These fixtures are mounted on the bed 52 in any suitable manner and arespaced apart so that the wheel and shield can be freely moved verticallytherebetwcen. The purpose for mov ing the wheel and shield vertically isto bring the wheel into engagement with a crushing roller 53 which isjournaled in a fixture 52 mounted on the table I 2 midway between thefixtures 44. To provide access to the wheel for the crushing roller thewheel shield is apertured at the bottom as indicated at 54 in Figure 1.

Coolant is supplied to the Wheel where it engages each or" theworkpieces by the flexible conduits 5 which are connected together andwith the outlet of the coolant pump 58 which draws coolant from areservoir 64}. It will be apparent that the supply of coolant from theseconduits is also eiiective for bathing the wheel during its dressingcycle due to the fact that all of the conduits direct their jets againstthe wheel at a level substantially higher than the said crushing roll.

In order properly to position the saddle and wheel in the verticaldirection when the wheel is retracted from the crushing roller followinga dressing cycle, the saddle may have a sto mounted thereon and whichabuts an able stop screw 5 carried on the column it. This provides forpositive alignment of the wheel with the workpieces during all grindingoperations.

The movement of the table [2 may similarly be limited by a stop member66 thereon which is adapted on each of its directions of movement toabut one or" the adjustable stop screws which are carried on the bed It.As will be seen hereinafter this provides a limit for the depth of outwhich the grinding wheel will take in the workpieces.

The motor Mi and M2 are adapted for being controlled by the controlcircuit indicated in Figure 4. In Figure 4 there are the power lines Liand L2 and therebetween is connected a contactor coil l6 which is inseries with a normally open push button 2. Bypassing the button 72 arethe normally open blades to of the armature 75 associated with the coiliii and serially arranged with the blades 74 is the blade it? of a limitswitch LS. The armature it also has normally open blade 88 in seriesbetween the power lines Li and L2 with the motor Mi. The motor M2 isalso connected between the power lines Li and L2 and in series with amanually operated switch 82 and the blades 84 also associated with thelimit switch LS.

Operation In operation, the parts of the grinding machine may occupy theposition shown in Figure 1. At this time the limit switch LS is engagedby the part 86 of the column [8 so that the blade l8 thereof is closedand the blade 8 is open. At this time the motor Ml can be energized byclosing a and traversed beneath the wheel.

the switch l2 which energizes the coil 15] to move the armature thereofupwardly thus closing the blades 74 and 80. The blades M provide aholding circuit for the said coil while the other of the blades at 89complete the energizing circuit for the motor MI. The Wheel is thusdriven at grinding speeds.

In order to grind the workpiece lil mounted in the fixture 44 the tableI2 is moved first in one direction to move one of the workpiecesradially inwardly toward the wheel and thereafter is reversed to movethe other of the workpieces radially inwardly toward the Wheel. It willbe observed that the grinding operation on each of the workpieces takesplace by a straight radial feeding movement of the wheel into theworkpiece. The are of contact of the wheel with the workpiece is thusquite small and relatively heavy feeds can be taken. At the same timethe jets issuing from the flexible conduits 53 impinge on the wheeldirectly at its area of contact with the workpiece and insure anadequate supply of coolant to the wheel.

The forming of a workpiece by moving it radially relative to the wheelis much more rapid than could be accomplished by mounting the workpieceon the table and traversing it past the wheel therebeneath. A much morerapid overall grinding cycle thus obtains.

As an example of an actual grinding operation workpieces an inch acrossand having a slot onehalf inch deep therein were ground on a machineaccording to former practices. That is, the workpieces were mounted onthe table of the machine These same workpieces were also mounted infixtures as indicated at 44 and ground by moving them radially into thewheel. The production of workpieces by the method and arrangement ofthis invention was substantially 14 times more rapid than by formermethods. It will be appreciated that this comes about because the wheelhas only a onehalf inch feeding stroke to make into the world piece whenarranged according to the present invention, whereas a stroke of seveninches of the table is necessary when the workpiece is; traversedbeneath the wheel.

After a predetermined number of grinding operations during which thetable is alternately moved first in one direction and then in the otherand during which time the finished workpiece is replaced by an ungroundworkpiece while the Wheel is operating on the other thereof, it becomesnecessary to reform the wheel to a true shape. the roll 59 and then ismoved downwardly by manipulation of the hand wheel 36. soon as the wheeland saddle commence to move downwardly the member 86 will permit theswitch LS to move so that the blade '58 thereof opens thus de-energizingthe coil '10 and the blade 84 thereof closes thus preparing the circuitfor the motor M2. De-energization of the coil it drops the armature l6and permits the blades 8%} thereof to open and to de-energize the motorMl.

After the wheel and roll have been brought together the switch 82 isclosed to energize the motor M2 which drives the wheel and roll atcrushing speed to carry out a dressing cycle. After the dressingoperation is completed the hand wheel 35 is moved in the oppositedirection and the saddle and wheel head are raised vertically until thestop member 62 is abutted by the screw 64. At this time the member 68actuates the switch LS whereupon the blade 84 thereof is At this timethe wheel is centered over a? opened and the blade is is closed. Thisde-energizes the motor M2 and prepares the control circuit for the motorM! which can then be energized by closing the switch 72.

It will be apparent from the foregoing discussion of the operation ofthis machine that a grinding operation according to this invention isvery simple and rapid to carry out, merely requiring that the table bereciprocated between two predetermined limits while ground workpiecesare continuously replaced by unground pieces.

It will also be noted that whenever the wheel is dressed, and which mayoccur after each grinding operation or after any given number ofgrinding operations, means are provided which prevents the wheel frombeing moved against the dressing roll while the said wheel is driven atgrinding speed. This prevents damage to the roll by careless orunskilled operation of the machine.

At the same time, the returning of the wheel to grinding positionfollowing a dressing operation on the said wheel is accompanied by anautomatic de-energization of the auxiliary motor which drives the wheelat crushing speed whereby the motor for driving it at grinding speed canbe energized without the possibility of damaging the auxiliary motor.

It will be understood that this invention is susceptible to modificationin order to adapt it to different usages and conditions and,accordingly, it is desired to comprehend such modifications within thisinvention as may fall within the scope of the appended claims.

I claim:

1. A grinding machine comprising, a support, a rotatably mountedgrinding wheel of given diameter secured on said support and verticallyreciprocable thereon and having a peripheral work surface, a tablepositioned on said support below and in spaced relation to said grindingwheel extending transversely thereto, said table including means forhorizontally reciprocating said table on said support, first and secondwork mounts for workpieces secured on said table one on each sideradially of said grinding wheel, said work mounts inclusive ofworkpieces mounted thereon defining therebetween a spacing greater thansaid given diameter of said grinding wheel, said work mounts beingadapted for the positioning of workpieces thereon in true radialdisposition to the work surface of said grinding wheel and being movableradially relatively to said grinding wheel with said table foralternately engaging the work pieces with said wheel, a rotatable crushforming roll secured on said table co-planar with said grinding wheeland interposed midway between said work mounts and having the worksurface thereof in true radial disposition relative to said grindingwheel for engagement therewith in planar movement, and means on saidsupport for driving said grinding wheel at grinding speed.

2. A grinding machine comprising, a support, a rotatably mountedgrinding wheel of given diameter secured on said support and verticallyreciprocable thereon and having a peripheral work surface, a tablepositioned on said support below said grinding wheel and extendingtransversely thereto, said table including means for horizontallyreciprocating said table on said support, first and second work mountsfor workpieces secured on said table one on each side radially of saidgrinding wheel, said work mounts inelusive of workpieces mounted thereondefining therebetween a spacing greater than said given diameter of saidgrinding wheel, said work mounts being adapted for the positioning ofworkpieces thereon in true radial disposition to the work surface ofsaid grinding wheel and being movable radially relatively to saidgrinding wheel with said table for alternately engaging the workpieceswith said wheel, a crush forming roll secured on said table co-planarwith and beneathsaid grinding wheel and interposed midway between saidwork mounts and having the work surface thereof in true radialdisposition relative to said grinding wheel for engagement therewith inplanar movement, and means including drive means on said support forselectively driving said grinding wheel at grinding speed and a speedless than said grinding speed.

3. A grinding machine comprising, a support including a bed and a columnextending vertically therefrom, a rotatably mounted grinding wheel ofgiven diameter secured on said column and vertically reciprocablethereon and having a peripheral work surface, said grinding wheel beingrotatable on an axis on said column, a table positioned on said bed inspaced relation to said grinding wheel, said table including means forhorizontally reciprocating said table on said bed, a first motor fordriving said wheel at grinding speed, a second motor for driving saidwheel at crushing speed, first and second work mounts for workpiecessecured on said table one on each side radially of said grinding wheel,work mounts inclusive of said workpieces mounted thereon definingtherebetween a spacing greater than said given diameter of said grindingwheel, said work mounts being adapted for the positioning of workpiecesthereon in true radial disposition to the work surface of said grindingwheel and being movable radially relatively to said grinding wheel withsaid table in reciprocation for alternately engaging the workpieces withsaid wheel, a crush forming roll secured on said table co-planar withand beneath said grinding wheel and interposed midway between said workmounts and having the work surface thereof in true radial dispositionrelative to said grinding wheel for engagement therewith in planarmovement, means including electric switching means on said columnresponsive to vertical movement of said grinding wheel towards saidcrush roll for open circuiting said first motor, and means including aswitch for energizing said second motor.

4. A method of grinding workpieces which comprises the steps of: fixedlymounting on a reciprocable bed in opposed relation and at a givenspacing therebetween a pair of workpieces to be ground, establishingtrue radial disposition between each of said workpieces to be ground anda circular grinding wheel of predetermined configuration and of lesserdiameter than said given spacing, said grinding wheel being interposedbetween said workpieces, moving one of said workpieces radially intoengagement with said grinding wheel while maintaining said spacing,grinding said one workpiece, moving the other of said workpiecesradially into engagement with said grinding wheel while maintaining saidspacing between said workpieces, grinding said other workpiece, andmoving said grinding wheel into contact with a crush roll mounted midwaybetween said workpieces while simultaneously disengaging said wheel fromeither of said workpieces, and rotating said grinding wheel at crushingspeed while in contact with said crush roll.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Ernst et a1 NOV. 5, 1935 Number 8Name Date Ward Apr. 20, 1937 Calame Aug. 19, 1941 Krueger Aug. 4, 1942Arms Nov. 3, 1942 Thomas June 29, 1945 Kavle May 29, 1945 Polk Sept. 25,1945 Polk et a1 Feb. 24, 1948 Polk July 27, 1948

